The invention relates generally to a gearbox, and more particularly to a gearbox with an input shaft and a clutch adapted to span an interruption in supply fluid to the gearbox.
Clutches are mechanical devices that provide for the transmission of torque and rotational movement from one component (the input driving member) to another (the output driven member) when engaged. Clutches are used when the transmission of torque and rotational movement needs to be controlled. Thus, clutches can be selectively engaged to transfer torque and rotational movement and then disengaged to halt transmission to the driven member.
One gearbox design utilizes a hydraulically actuated clutch with a pressure plate for engaging and holding clutch lock-up for transmission purposes. Hydraulic pressure is applied to the clutch to sustain the clutch engagement.
One criteria for clutch designs in some aerospace applications is that clutch designs cannot permit interruption of positive power transfer during aircraft maneuvers. With a hydraulically actuated clutch design, an interruption in a fluid supply to the clutch can result in clutch disengagement. Fluid supply interruption occurs with a loss of oil intake at supply pumps. This interruption can happen during certain aircraft maneuvers when fluid goes to a top of a supply tank away from the pump intake at a bottom of the tank. Erratic control of the aircraft, damage to the drive line and gears, and plate wear are all possible problematic side effects that can be directly traced to an interruption in the fluid supply to the clutch.